Datasheet

769
SAM9X25 [DATASHEET]
11054E–ATARM–10-Mar-2014
38.10.5.5 Reversal after a Repeated Start
Reversal of Read to Write
The master initiates the communication by a read command and finishes it by a write command.
Figure 38-31 on page 769 describes the repeated start + reversal from Read to Write mode.
Figure 38-31.Repeated Start + Reversal from Read to Write Mode
Note: 1. TXCOMP is only set at the end of the transmission because after the repeated start, SAD is detected again.
Reversal of Write to Read
The master initiates the communication by a write command and finishes it by a read command. Figure 38-32 on page
769 describes the repeated start + reversal from Write to Read mode.
Figure 38-32.Repeated Start + Reversal from Write to Read Mode
Notes: 1. In this case, if TWI_THR has not been written at the end of the read command, the clock is automatically stretched
before the ACK.
2. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
S SADR R ADATA 0A DATA 1
SADRSr
NA
W A DATA 2 A DATA 3 A P
Cleared after read
DATA 0 DATA 1
DATA 2 DATA3
SVACC
SVREAD
TWD
TWI_THR
TWI_RHR
EOSACC
TXRDY
RXRDY
TXCOMP
As soon as a START is detected
S SADR W ADATA 0A DATA 1
SADRSr
A
R A DATA 2 A DATA 3 NA P
Cleared after read
DATA 0
DATA 2 DATA3
DATA 1
TXCOMP
TXRDY
RXRDY
As soon as a START is detected
Read TWI_RHR
SVACC
SVREAD
TWD
TWI_RHR
TWI_THR
EOSACC